Water Supply & DistributionQuestion 37 of 360
What is the essential difference between back-siphonage and backpressure backflow?
a.Back-siphonage is caused by negative (sub-atmospheric) pressure in the supply, while backpressure is caused by downstream pressure exceeding supply pressure
b.They are identical
c.Back-siphonage requires a pump; backpressure never does
d.Backpressure only occurs in drainage systems
Explanation
Back-siphonage results from negative pressure (a partial vacuum) in the supply pulling water backward, while backpressure occurs when downstream pressure exceeds the supply and pushes water backward. They are not identical, back-siphonage does not require a pump, and backpressure occurs in pressurized water systems, not just drainage.
Law Reference: 2022 California Plumbing Code (CPC) §603.0Practice all 360 questions free — no signup required.
Related questions on this topic
- A fixture requires a minimum flow (residual) pressure of 8 psi to operate correctly. During peak demand your calculation shows only 5 psi available at that fixture. What is the correct interpretation?
- Which characteristic makes CPVC acceptable for hot water distribution where standard PVC is not?
- A pressure-reducing valve is set to deliver 65 psi downstream from a 110 psi street pressure. On a closed system, what additional device is commonly required to accompany the PRV?
- A meter and service are being sized. The peak demand is 24 gpm at a required 20 psi residual. Available static street pressure is 55 psi, and the total pressure loss budget (meter, elevation, friction, fittings) is calculated at 40 psi. Is the design feasible?
- Which joining method is appropriate for Type L copper water tube?
- A mechanical water hammer arrestor uses a sealed piston or bellows with a gas charge. Why is this preferred over an old-style capped air chamber?
Last reviewed: · editorial process
PrepPass Editorial Team · Verified against California CSLB C-36 Plumbing Trade Examination · How we review